Geothermal energy is generated from the radioactive decay that is taking place within the core of the Earth. The core is at temperatures of around 6000°C and heat dissipates outwards from the core to the crust.
Geothermal energy is exploited by drilling a well to depths of 1 km or more (abstraction well) and pumping water from the ground, removing heat from it and then returning the water to the same geological formation through a second well (reinjection well) i.e. it is a conservative system and any fluids removed are replaced. The combined wells are often referred to as a geothermal doublet.
During the oil crisis of the 1970s, the geothermal potential of the whole of the UK was mapped by BGS, concluding that the heat resource was around 100 GW thermal with the possibility for some power generation.
This is chielfy due to competition from fossil energy resources. Rising energy prices, resource depletion and concerns about energy security and climate change mean that there is renewed interest in deep geothermal as a low carbon source of energy.
The UK already has one deep geothermal energy scheme at Southampton that has been operating for the past 25 years. This scheme provides heat to a range of domestic and industrial users.
The exploitation of geothermal energy does not rely upon fracking. Geological units that are capable of supplying water without additional stimulation are the ideal target.
The potential of the resource needs to be promoted to government and commerce to encourage investment in this form of low carbon energy.
Yes, there are similar resources elsewhere that have already been developed, for example in France (Paris Bains), Germany (Soultz project), Hungary (Panonian Basin) and at several sedimentary basins in China.